Let's not forget that Mikey requested the #11 when Des retired, he was turned down (and given Palmer's old number) - sometime later Sheridan was given the #11. During the Double Steve period they dismissed any relevance to a 'lineage' with jumper numbers - I think, just to p$ss off the rusted-ons. No doubt that gave them great amusement in the boredroom. That all changed when Pav retired - I knew they couldn't just hand it off to some pimple-faced draftee from country Vic.
So no, Walters could not wear whatever number he wanted - still can't (I assume).